172 305 25 07-01
Flame monitoring and measure-
ment of ionisation current
The burner is monitored according
to the ionisation principle. Check the
ionisation current on start-up and on
each service call.
The reason for a low ionisation current
may be leaking currents, bad connec-
tion to earth, dirt or a faulty position
of the flame electrode in the burner
head. Sometimes also a faulty gas/air
mixture may cause too weak a ionisation
current.
The ionisation current is measured
by means of a microampere meter
(µA) connected in series with the
flame electrode and the gas burner
control.
Connect the µA-meter, see figure. Min.
required ionisation current according
to table. In practice this current must
be considerably higher, preferably
more than 10 µA. All the gas burners
are equipped with a ionisation cable
that can be slit which facilitates the
connection of the µA-device.
Gas pressure switches:
Adjustment range:
2,5-50 mbar GW 50
5-150 mbar GW 150
Adjustment of min. gas pressure
switch
The min. pressure switch should react
if the gas pressure is too low and
prevent the burner from starting. Too
low a gas pressure during operation
should stop the burner. The burner
may start again when the rated gas
pressure has been reached.
Remove the protective cover. Connect
a pressure gauge for measuring the
rated pressure. Decide on pressure
at which the gas switch should switch
off. Set this pressure by means of the
valve. Carefully turn the knob (see
figure) until the gas pressure switch
switches off. The value shown on the
scale should then approximately cor-
respond with the value shown on the
pressure gauge. Tolerance on scale
appr. ± 15 %. Open the ball valve.
GENERAL INSTRUCTION
Adjustemnt of max. gas pressure
switch
The burner is equipped with a max.
gas pressure switch only on request.
It should stop the burner if the gas
pressure exceeds the set value. The
burner can then only be re-started
manually (gas burner control or
overpressure switch).
Remove the protective cover. Connect
a pressure gauge for measuring the
rated gas pressure. Decide on pres-
sure at which the gas pressure switch
should switch off. Turn the adjustment
knob to this value. Tolerance on the
scale ±15%.
Adjustment of air pressure switch
The air presure switch should stop the
burner if the air volume is reduced.
The air proving device shall be adjusted
in such a way that if there is insufficient
air supply at the highest or lowest
burner operating stage, the device
operates before the supervised pres-
sure is less than 80% of the pressure
at the controlled stage and the CO
content of the combustion products
exceeds 1% by volume.
Air pressure switch:
Adjustment range ca:
1-10 mbar LGW 10
2,5-50 mbar LGW 50
Flame monitoring
Gas pressure switch, air pressure
switch
Gas control
Connection to terminal
in gas control
Min. ionisation
current required
LMG
1
2 µ A
LGB
1
10 µ A
LFL
24
10 µ A
MMI 810
2
5 µ A
TMG 740-3
1
5 µ A
